I also agree a better tank is better, because the more space you have per fish the better they will live (every book tells you how to measure this). I also recommend you get an oversized filter, some aquariums come with a complete package including the filter. And in regards to the fish you want to put in, there is two books that I recommend because, besides telling you how to setup your aquarium, it tells the suitable companions and the unsuitable companions for every fish in the book, as well as the water requirements, origin and feeding.
Pocket Guide To The Care and Maintenance of Aquarium Fish by Alice Burkhart, Richard Crow and Dave Keely, PRC
Aquarium Fish, Ulrich Schliewen. Barrons
Pocket Guide To The Care and Maintenance of Aquarium Fish by Alice Burkhart, Richard Crow and Dave Keely, PRC
Aquarium Fish, Ulrich Schliewen. Barrons